The present invention relates to a front fork for a motorcycle.
Jikkai Hei 2-24140 published by the Japanese Patent Office in 1988 discloses a front fork which absorbs mechanical vibration caused by road unevenness, and thereby improves a ride comfort.
The repulsive force of the front fork is increased by the degree of contraction amount of the front fork by providing an air chamber in the upper part of a reservoir which contracts according to an oil pressure.
When the front fork contracts at high speed, for example when the motorcycle is suddenly braked, the repulsive force must be greatly increased compared to a usual contraction so as to maintain the motorcycle body in a correct orientation. However, with a front fork discussed above, the same repulsive force as during normal contraction could only be obtained in such situations.
It is therefore an object of this invention to suitably increase the repulsive force of the front fork when the front fork contracts at high speed during sudden braking, etc., while at the same time absorbing the mechanical vibration caused by road unevenness during normal running.
In order to achieve the above object, this invention provides a front fork for a motorcycle, comprising a first tube and second tube which are fitted together, a damper including a cylinder fixed to the second tube, a rod fixed to the first tube and inserted in the cylinder and a piston fixed to one end of the rod and housed inside the cylinder, and a reservoir connected to the cylinder. The reservoir includes a flow restriction part midway along its length, a first air chamber above the flow restriction part which is compressed according to an oil pressure, and a second air chamber below the flow restriction part which is compressed according to an oil pressure.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.